This invention relates to airless paint sprayers, and more particularly, to a mechanism for providing a more consistent spray of paint without a loss of pressure over a range of operating parameters.
In a typical airless paint sprayer, a piston driven diaphragm pulls the paint from a supply line into a paint holding or diaphragm chamber. A spray gun has a trigger which, when depressed, opens a valve to allow the pressurized paint in the chamber to flow to a gun nozzle and atomize as it exits a paint orifice for spraying onto a surface to be coated.
Airless paint sprayers commonly include a suction tube inserted within a can of paint through which the paint is delivered to the diaphragm chamber. Suction is created in the suction tube by a deformable diaphragm which is secured around its perimeter. A central portion of the diaphragm is oscillated, by a piston-driven hydraulic system, for example, between a convex and a concave configuration to thereby pull the paint toward the diaphragm and hence force it outwardly to the spray gun.
In another format, a rotating eccentric cam drives a bearing which in turn drives a piston. The piston is coupled to the diaphragm and the rotation of the cam drives the piston to thereby move the diaphragm to and between the convex and concave configurations. The paint is drawn from the can through the suction tube and inlet valve toward the diaphragm and into the diaphragm chamber to be discharged through the spray gun.
Despite past efforts, the use of such systems for spraying paint, for example, have been subject to inconsistent results and unexplained, undesirable variations. For example, on a given day, a system may not work well with one paint, failing to fully atomize it and "spattering" it onto a surface while operating efficiently with the same paint at another time or in another location.
Other problems which are commonly identified in such airless paint sprayers include ineffective spraying of paint of a first type but efficient spraying of paint of a second type. Several possible causes of problems of this type have been proposed such as lack of consistent priming, paint buildup, clogged filters, paint viscosity, humidity, etc. However, these problems occur even when a problem paint is thinned to the general consistency of water, the filters are clean, or the flow path of the paint unclogged. These symptoms can even be apparent in using one paint while not in using another even though the paints have similar viscosities.
Accordingly, the effective and consistent use of an airless paint system appears to be a sometimes thing dependent on a variation of parameters, ever changing.
Therefore, it is apparent that there is a need for an airless paint sprayer which does not exhibit a loss of pressure while spraying and can reliably, efficiently and effectively spray all types of paint at a wide range of operating conditions without the above identified problems and inconsistencies.
It has thus been a primary objective of this invention to provide an improved airless paint sprayer which does not loose pressure while spraying.
It has been a further objective of this invention to provide such a paint sprayer which can be efficiently and effectively used with a variety of paint types without loosing pressure while spraying.
It has been a still further objective of this invention to provide such a paint sprayer which can be used with a variety of paints and paint viscosities to consistently atomize and spray the paint in a desired homogeneous pattern.